Electrophotographic image-forming or marking systems and machines are used to transfer images onto paper or other medium in both printing, copying and facsimile systems. Generally, a photoconductor is selectively charged and optically exposed to form an electrostatic latent image on the surface. Toner is deposited onto the charged photoconductor surface. The toner has a charge, thus it will adhere to the photoconductor surface in areas corresponding to the electrostatic latent image. The toner image is transferred to the paper or other medium. The toned paper is heated by a fuser roller system for the toner to fuse to the paper. The photoconductor is then refreshed—cleaned to remove any residual toner and charge—to make it ready for another image. The imaged paper is then passed to a document output collection area or tray where the user collects the finished, permanently imaged paper or documents.
In this type of marking system, an original to be copied is generally placed upon a platen glass where it is scanned to form a latent electrostatic image on the photoreceptor. This latent image is eventually transferred to a final receiving member such as paper. If there are any marks or debris on the platen glass, these imperfections usually visibly show up on the final copy. For this reason, it is always recommended that the platen glass be kept clean and free of debris and other unwanted marks.
In some large offices, especially those concerned with security, printers, marking apparatus, copiers and duplicators are modified so that a code or identification means for the user is required before the marking apparatus becomes functional. In many such systems, a favored procedure is to require the fingerprints of the user for authentication before he or she could use the apparatus. In addition to user identification, law enforcement agencies, both public and private, take fingerprints of individuals for storage and later reference. This could be quite common at local police stations, governmental agencies such as the FBI and other agencies or private security firms.
To accomplish this imaging of fingerprints, the individual or subject's finger or thumb is placed on the platen glass and an electrophotographic image of his or her fingerprints are obtained. In placing the subject's hand or fingers on the platen, a residual oil from the subject's hand usually is left on the platen glass. This oil or some perspiration is reproduced and later could adversely affect the quality of other images commonly made on an electrophotographic apparatus. If the user forgets or neglects to wipe the platen glass clean after fingerprinting, subsequent copies will need to be repeated after the platen glass is cleaned of debris.